Resistive memory cell with intrinsic current control

ABSTRACT

Providing for a two-terminal memory cell having intrinsic current limiting characteristic is described herein. By way of example, the two-terminal memory cell can comprise a particle donor layer having a moderate resistivity, comprised of unstable or partially unstable metal compounds. The metal compounds can be selected to release metal atoms in response to an external stimulus (e.g., an electric field, a voltage, a current, heat, etc.) into an electrically-resistive switching medium, which is at least in part permeable to drift or diffusion of the metal atoms. The metal atoms form a thin filament through the switching medium, switching the memory cell to a conductive state. The moderate resistivity of the particle donor layer in conjunction with the thin filament can result in an intrinsic resistance to current through the memory cell at voltages above a restriction voltage, protecting the memory cell from excessive current.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 62/111,383 filed Feb. 3, 2015 and titled RESISTIVEMEMORY CELL WITH INTRINSIC CURRENT CONTROL, which is hereby incorporatedfor reference herein in its entirety and for all purposes.

INCORPORATION BY REFERENCE

The present invention incorporates, by reference and for all purposes,application Ser. No. 11/875,541 filed Oct. 19, 2007 and application Ser.No. 12/575,921 filed Oct. 8, 2009.

TECHNICAL FIELD

This disclosure generally relates to resistive switching memory that hasbuilt-in current control, which enhances device reliability and reducescomplexity of control circuits.

BACKGROUND

Resistive-switching memory represents a recent innovation within thefield of integrated circuit technology. While much ofresistive-switching memory technology is in the development stage,various technological concepts for resistive-switching memory have beendemonstrated by the inventor(s) and are in one or more stages ofverification to prove or disprove associated theories or techniques. Theinventor(s) believe that resistive-switching memory technology showscompelling evidence to hold substantial advantages over competingtechnologies in the semiconductor electronics industry.

The inventor(s) believe that resistive-switching memory cells can beconfigured to have multiple states with distinct resistance values. Forinstance, for a single bit cell, the restive-switching memory cell canbe configured to exist in a relatively low resistance state or,alternatively, in a relatively high resistance state. Multi-bit cellsmight have additional states with respective resistances that aredistinct from one another and distinct from the relatively lowresistance state and the relatively high resistance state. The distinctresistance states of the resistive-switching memory cell representdistinct logical information states, facilitating digital memoryoperations. Accordingly, the inventor(s) believe that arrays of manysuch memory cells, can provide many bits of digital memory storage.

The inventor(s) have been successful in inducing resistive-switchingmemory to enter one or another resistive state in response to anexternal condition. Thus, in transistor parlance, applying or removingthe external condition can serve to program or de-program (e.g., erase)the memory. Moreover, depending on physical makeup and electricalarrangement, a resistive-switching memory cell can generally maintain aprogrammed or de-programmed state. Maintaining a state might requireother conditions be met (e.g., existence of a minimum operating voltage,existence of a minimum operating temperature, and so forth), or noconditions be met, depending on the characteristics of a memory celldevice.

The inventor(s) have put forth several proposals for practicalutilization of resistive-switching technology to includetransistor-based memory applications. For instance, resistive-switchingelements are often theorized as viable alternatives, at least in part,to metal-oxide semiconductor (MOS) type memory transistors employed forelectronic storage of digital information. Models of resistive-switchingmemory devices provide some potential technical advantages overnon-volatile FLASH type transistors.

In light of the above, the inventor(s) desire to continue developingpractical utilization of resistive-switching technology.

SUMMARY

The following presents a simplified summary of the specification inorder to provide a basic understanding of some aspects of thespecification. This summary is not an extensive overview of thespecification. It is intended to neither identify key or criticalelements of the specification nor delineate the scope of any particularembodiments of the specification, or any scope of the claims. Itspurpose is to present some concepts of the specification in a simplifiedform as a prelude to the more detailed description that is presented inthis disclosure.

Various embodiments of the present disclosure provide for a two-terminalmemory cell having intrinsic current limiting characteristics. In somedisclosed embodiments, the two-terminal memory cell can comprise aparticle donor layer having a moderate resistivity, comprised ofunstable or partially unstable metal compounds. The metal compounds canbe selected to release metal atoms in response to an external stimulus(e.g., an electric field, a voltage, a current, heat, etc.). Moreover,the metal atoms can be ionized in response to the external stimulus, andas metal ions be highly conductive. The memory cell can also include anelectrically-resistive switching medium that is at least in partpermeable to drift or diffusion of the metal atoms. In response to theexternal stimulus, the metal atoms diffuse from the particle donor layerto the switching medium. Upon removal of the external stimulus, themetal atoms become trapped within defects (grain boundaries, vacancies,etc.) of the switching medium, and form a highly conductive thinfilament or path through the switching medium. In addition to theforegoing, the moderate resistivity of the particle donor layer inconjunction with the thin filament can result in an increased resistanceto current flow through the memory cell at voltages above a restrictionvoltage. The increased resistance to current can protect the memory cellfrom detrimental effects of excessive electrical current, even in theabsence of external current compliance (e.g., current-compliancefacilitated by circuitry external to the memory cell).

In further embodiments, a 1 transistor-n resistive cell (1T-nR, where nis a suitable positive integer) memory architecture is provided havinghigh operational bandwidth. The 1T-nR memory architecture can comprise arow of n disclosed two-terminal memory cells connected to a singleselect transistor (e.g., complementary metal oxide semiconductor (CMOS)transistor) for activation/deactivation. The memory architecture canapply a program voltage across the row, without external currentcompliance, while mitigating or avoiding excess current at respectivememory cells on the row. This facilitates a memory architecture havinghigh performance of two-terminal memory, in conjunction with high memorydensity (e.g., by avoiding additional current compliance for each cellof a 1T-nR memory architecture), high operational bandwidth (e.g., ashigh as a full row(s) of cells), with enhanced longevity and resistanceto catastrophic failure. Accordingly, the disclosed embodimentscontribute significant advancements to existing memory technologies.

In an embodiment, there is disclosed a non-volatile memory cell. Thenon-volatile memory cell can comprise a bottom electrode, and anelectrically-resistive switching layer above the bottom electrode thatis at least in part permeable to movement of the current-carryingparticles within the electrically-resistive switching layer. Further,the non-volatile memory cell can comprise a particle donor layer abovethe electrically-resistive switching layer that provides conductingparticles to the electrically-resistive switching layer in response to astimulus, wherein the particle donor layer has an electrical resistivityof about 0.5 milliohm (mohm)-centimeter (cm) or greater. Moreover, thenon-volatile memory cell can comprise a top electrode, wherein: the topelectrode, particle donor layer, electrically-resistive switching layerand bottom electrode are disposed electrically in serial.

In other embodiments, the subject disclosure provides a semiconductordevice comprising a semiconductor substrate including a plurality ofCMOS devices and a resistive memory device disposed upon thesemiconductor substrate and connected to a CMOS device of the pluralityof CMOS devices. Further, the resistive memory device can comprise abottom electrode and a resistive switching material layer disposed uponthe bottom electrode, wherein the resistive switching material layercomprises a plurality of defect locations, and wherein a resistivity forthe resistive switching material layer is larger than about 0.5 ohm-cm.In addition to the foregoing, the resistive memory device can comprise aresistive layer disposed upon the resistive switching material layer,wherein the resistive layer comprises metal atoms and a metal compound,wherein a plurality of metal atoms from the resistive layer diffuse todefect locations from the plurality of defect locations in the resistiveswitching material, and wherein the resistive layer is characterized bya resistivity within a range of about 0.5 milliohm-cm to about 0.1ohm-cm. The resistive switching device can further comprise a topelectrode disposed upon the resistive layer.

The following description and the drawings set forth certainillustrative aspects of the specification. These aspects are indicative,however, of but a few of the various ways in which the principles of thespecification may be employed. Other advantages and novel features ofthe specification will become apparent from the following detaileddescription of the specification when considered in conjunction with thedrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Numerous aspects, embodiments, objects and advantages of the presentinvention will be apparent upon consideration of the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich like reference characters refer to like parts throughout. In thisspecification, numerous specific details are set forth in order toprovide a thorough understanding of this disclosure. It should beunderstood, however, that certain aspects of the subject disclosure maybe practiced without these specific details, or with other methods,components, materials, etc. In other instances, well-known structuresand devices are shown in block diagram form to facilitate describing thesubject disclosure;

FIG. 1 depicts a block diagram of an example memory cell havingintrinsic current limiting characteristics, according to one or moreembodiments;

FIG. 2 illustrates block diagrams of example memory devices according tofurther embodiments;

FIG. 2A depicts block diagrams of example memory devices facilitatingcontrolled conductivity in a memory device according to otherembodiments;

FIG. 3 depicts a block diagram of an example memory cell in response toa reverse bias, in an embodiment(s);

FIG. 4 depicts a block diagram of an alternative memory cell withintrinsic current limiting characteristics, in another embodiment;

FIG. 5 illustrates a block diagram of example filament formation for thealternative memory cell, in one or more embodiments;

FIG. 6 depicts a block diagram of example filament deformation for thealternative memory cell in further embodiments;

FIG. 7 illustrates a diagram of an example current-voltage response fora disclosed memory cell, in other embodiments;

FIG. 8 depicts a diagram of a sample 1T-nR memory architecture havinghigh operational bandwidth, in further embodiments;

FIG. 9 illustrates a flowchart of an example method for fabricating atwo-terminal memory having intrinsic current compliance, in anembodiment;

FIG. 10 depicts a flowchart of a sample method for fabricating atwo-terminal memory with intrinsic current compliance in anotherembodiment;

FIG. 11 illustrates a flowchart of an example method for fabricating atwo-terminal memory having intrinsic current compliance in furtherembodiments;

FIG. 12 illustrates a block diagram of an example electronic operatingenvironment in accordance with certain embodiments of this disclosure;

FIG. 13 illustrates a block diagram of an example computing environmentin accordance with certain embodiments of this disclosure.

DETAILED DESCRIPTION Introduction

One area of continued research for improvement in non-volatile memorydevices is higher memory density, which translates into greater storagecapacity per device. One solution is to progress to smaller technologynodes, enabling a greater number of smaller devices to be provided on agiven amount of chip space. In the last decade, memory devices havebroken the 100 nanometer (nm) scale, and have continued to progress to65 nm, 45 nm, 32 nm, and so on. However, for conventional memory, suchas NAND or NOR memory technology, several performance and longevityissues have arisen at sub-100 nm technologies.

Two-terminal memory has emerged to provide alternatives to NAND and NORmemory, without many of the problems associated with conventional memoryat sub-100 nm nodes. For instance, the inventors of the presentdisclosure are cognizant of resistive-switching memory technologies thathave higher overall performance and longevity than conventionalmemories, even at 20 nm nodes and below. One mechanism the assignee ofthe present disclosure has proposed for improved memory density isreferred to as a 1T-nR memory architecture, where n is a suitablepositive number (e.g., 128, 256, 512, 1024, 2048, etc.). Although CMOStransistors on a substrate surface can have problems below, e.g., 40 nm,the inventors believe that two-terminal memories will be quite robustwell below 20 nm. Accordingly, a memory architecture that has largenumbers of two-terminal memory devices (nR) and few CMOS transistors(1T) can achieve very high memory densities in two-terminal memoryarchitectures.

The inventors have identified one challenge with the 1T-nR memoryarchitecture addressed by disclosed embodiments. At an operationallevel, high operational bandwidth is a desired aspect of a memorydevice. The operational bandwidth determines a number of memory cellsthat can be programmed or erased with a single operation. Higherbandwidth can result in faster overall program and erase times for sucha device. However, a greater amount of current is consumed whenprogramming large numbers of memory cells. To keep from over-heating amemory cell, the inventors have proposed memory circuits that utilizecurrent compliance circuitry for each cell or a group of cells, toreduce probability of damaging individual cells. In a 1T-nR architecturewith high n, however, the transistor is the single point of externalcurrent compliance. Therefore, through a single point, the large amountof current must be supplied to the n two-terminal memory cells. Withoutcurrent compliance for individual cells, the inventors have recognizedthat a single cell or small group of cells can receive an excessiveamount of current, risking damage to the cell. Accordingly, theinventors have provided various embodiments in which aresistive-switching memory cell comprises intrinsic current limitingcharacteristics, to resist excess current through the memory cell andmitigate or avoid memory cell damage even in conjunction with highbandwidth memory operations. Furthermore, disclosed memory cells havingintrinsic current limiting features can be operated with less complexmemory control circuitry, simplifying architecture design; and enablingmemory cells to scale to lower process nodes, without changing theprocess.

Examples of two-terminal memory technology include resistive memory(e.g., resistive-switching memory cell), ferromagnetic memory, phasechange memory, magneto-resistive memory, organic memory, conductivebridging memory, and so on. Embodiments of the subject disclosure canprovide a filamentary-based memory cell. One example of afilamentary-based memory cell can comprise: a conductive layer (e.g.TiN, TaN, TiW) or a conductive silicon (Si) bearing layer (e.g., dopedpolysilicon, polycrystalline SiGe, etc.) a resistive switching layer(RSL) having crystalline defects or defect regions (e.g. amorphoussilicon, intrinsic silicon, non-stoichiometric oxide, non-stoichiometricsilicon oxide); and an active metal layer for providing filament formingparticles to the defect regions of RSL. In various examples, the activemetal layer can include, among others: silver (Ag), copper (Cu), gold(Au), titanium (Ti), nickel (Ni), aluminum (Al), chromium (Cr),tantalum(Ta), iron (Fe), manganese (Mn), tungsten (W), vanadium (V),cobalt (Co), platinum (Pt), and palladium (Pd), alloys of such metals,as well as materials rich in such metals, such as non-stoichiometricmetal compounds. Other suitable conductive materials, as well ascompounds or combinations of the foregoing can be employed for theactive metal layer in some aspects of the subject disclosure. In variousembodiments, particles of metal derived from the active metal layerbecome trapped within the defect regions (e.g. voids, grain boundaries,or the like) of the RSM. These trapped particles are neutral metalparticles that form conductive filaments within the RSM. Some detailspertaining to embodiments of the subject disclosure similar to theforegoing example can be found in the following U.S. patent applicationsthat are licensed to the assignee of the present application for patent:application Ser. No. 11/875,541 filed Oct. 19, 2007 and application Ser.No. 12/575,921 filed Oct. 8, 2009, each of which are incorporated byreference herein in their respective entireties and for all purposes.

In some aspects, the two-terminal memory can comprise 20 nanometer (nm)technology, whereas in other aspects the two-terminal memory cancomprise sub-20 nanometer technology (e.g., 15 nm, 10 nm, 5 nm, andothers). Moreover, the two-terminal memory can have a component areathat is less than about 5 F² (e.g., about 4.28 F²). In some aspects,three-dimensional stacks of two-terminal memory arrays can be provided,reducing component area. For instance, a 4.28 F² device can have aneffective component area of 2.14 F² for a three-dimensional devicehaving two stacked layers. As another example, the 4.28 F² device canhave an effective component area of 1.07 F² for a three-dimensionaldevice having four stacked layers, and so on. In the case of multi-levelcells (MLC), two stacked layers of cells that can represent two bits ofdata per cell can have an effective component area of 1.07 F², andbetter component area metrics can be achieved by either increasing thenumber of stacks or the number of bits represented by the cells.

Description of Example Embodiments

Referring now to the drawings, FIG. 1 illustrates a block diagram of anexample two-terminal memory cell 100 having intrinsic current limitingcharacteristics, according to one or more disclosed embodiments. Invarious embodiments, two-terminal memory cell 100 can be formed on asemiconductor substrate as part of an array of two-terminal memory. Insome embodiments, memory cell 100 can be formed with front-end-of-linefabrication techniques. In other embodiments, memory cell 100 can beformed with backend-of-line fabrication techniques.

Memory cell 100 comprises a bottom electrode 108. Bottom electrode 108is a conductive material, and can include TiN, TaN, W, WN, TiW or asuitable alloy of the foregoing, in some embodiments. In otherembodiments, bottom electrode 108 can be a conductive silicon material,such as a polysilicon, a doped polysilicon, a polycrystalline SiGe, adoped polycrystalline SiGe, and so forth. Over bottom electrode 108 is aswitching layer 106. Switching layer 106 can comprise anelectrically-resistive material, which is at least in part porous toconductive particles (e.g., metal ions, oxygen vacancies, etc.). Invarious embodiments, switching layer 106 can further comprise defectsites in which conductive particles can become trapped in the absence ofa suitably strong external stimulus. Accordingly, conductive particlescan migrate within switching layer 106 until encountering a defect site.Particles are less likely to move out of defect sites absent a suitablestimulus to force them out. Therefore, particles diffusing or driftingwithin switching layer 106 will accumulate within defect sites. Invarious embodiments, switching layer 106 can be comprised of aSi-bearing material, a solid electrolyte, a metal oxide, a metalnitride, or the like. In an embodiment, switching layer 106 can have amaterial resistivity of greater than about 0.5 ohm-cm. In anotherembodiment, switching layer 106 can be selected from a range of about 2nm to about 100 nm.

Memory cell 100 can further comprise a particle donor layer 104 overswitching layer 106. Particle donor layer 104 can comprise a metalcompound having an unstable or semi-stable state. Further, the metalcompound can be selected to have a material resistivity between about0.5 milliohm-cm (mohm-cm) and about 100 mohm-cm, in one or moreembodiments. In an embodiment, particle donor layer can be selected froma range of about 5 nm to about 200nm thick. In response to a suitablestimulus (e.g., an electric field, a current, a voltage, joule heating,and so on), some of the metal compounds can separate into free metalatoms and metal ions, and diffuse (or drift) into switching layer 106.The material resistivity of particle donor layer 104 can result in arelatively narrow width for this diffusion, resulting in a thin filamentof metal ions drifting into switching layer 106 in response to thestimulus. In contrast, high purity metal donor layers tend to have muchlower resistivity. For instance, silver, copper, aluminum, platinum,gold and other active metals suitable for donating particles to neighborlayers have resistivity values between about 0.0109 milliohm-cm (e.g.,for platinum) to about 0.00159 milliohm-cm (e.g., for silver). Materialswith these much lower resistivity values will result in significantlyhigher current in memory cell 100 in response to formation of acontinuous conductive filament through switching layer 106. This highercurrent will facilitate formation of a wider, thicker conductivefilament, facilitating the higher current flow throughout memory cell100. Thus, the low resistivity of metal ion donor layers provide apositive feedback mechanism (in forming thicker filaments) forincreasing current in memory cell 100. Particle donor layer 104, incontrast, can mitigate or avoid this positive feedback, to form thinconductive filaments that mitigate increase in current through memorycell 100—when conductive—in response to a rising voltage (e.g., avoltage rising above a program threshold voltage that causes memory cell100 to switch to the conductive state; a voltage within a range selectedfrom about 1 v to about 3.3 volts, or other suitable voltage or range ofvoltages). In absence of the stimulus, the particles can becomenon-ionic (e.g., metal atoms) and remain trapped within defect sites ofswitching layer 106, maintaining the filament of metal ions.

A second stimulus (e.g., having opposite polarity) can re-ionize themetal particles and cause them to drift back toward particle donor layer104, discontinuing the filament (in the physical and electrical sense).Accordingly, in response to the stimulus a high-conductive path of metalparticles can form across the switching layer, lowering an effectiveresistance of memory cell 100. In response to the second stimulus themetal particles can move back toward particle donor layer 104, breakingcontinuity of the filament, and restoring a high resistance state ofmemory cell 100. In at least one embodiment, the metal particles ofparticle donor layer 104 can be selected from a group consisting of: Ti,Ta, Al, Cu and Ag.

In some embodiments, memory cell 100 can comprise a top electrode 102formed above particle donor layer 104. In at least one embodiment, topelectrode 102 can be a metal wire of a memory array (e.g., a wordline, abitline, a sourceline, etc., see FIG. 8, infra). In other embodiments,top electrode 102 can be a conductive plug that electrically connectsparticle donor layer 104 to the metal wire of the memory array. Topelectrode 102 can be comprised of a suitable electrical conductor, suchas a metal (e.g., Al, Cu, Ag, and so forth in conjunction with optionalbarrier material or adhesion material, including Ti, TiN, TaN, TiW, orthe like, below or above the conductor layer), a conductive silicon(e.g., doped polysilicon, doped polycrystalline SiGe, etc.), or thelike.

In various embodiments, particle donor layer 104 can be selected to havea second material resistivity in proportion to a first materialresistivity of switching layer 106. In some embodiments, the proportioncan be about 1:5; in other embodiments the proportion can be about1:1000; whereas in still other embodiments the proportion can beselected from a range between about 1:5 and about 1:1000. In furtherembodiments, the proportion of second material resistivity of particledonor layer 104 to the first material resistivity of switching layer 106can be larger than 1:1000 (e.g., 1:5000, 1:10,000, 1:100,000, etc.).

In further embodiments, particle donor layer 104 can comprise a metalnitride selected from the group consisting of: TiN_(x), TaN_(x),AlN_(x), CuN_(x), WN_(x) and AgN_(x), where x is a positive number. Inother embodiments, particle donor layer 104 can comprise a metal oxideselected from the group consisting of: TiO_(x), TaO_(x), AlO_(x),CuO_(x), WO_(x) and AgO_(x). In other embodiments, particle donor layer104 can comprise a metal oxi-nitride selected from the group consistingof: TiO_(a)N_(b), AlO_(a)N_(b), CuO_(a)N_(b), WO_(a)N_(b) andAgO_(a)N_(b), where a and b are positive numbers. In another embodiment,switching layer 106 can comprise a material selected from the groupconsisting of: SiO_(y), AlN_(y), TiO_(y), TaO_(y), AlO_(y), CuO_(y),SiN_(X), TiN_(X), TiN_(y), TaN_(x), TaN_(y), SiO_(x), AlN_(x), CuN_(x),CuN_(y), AgN_(x), AgN_(y), TiO_(x), TaO_(x), AlO_(x), CuO_(x), AgO_(x),and AgO_(y), where x and y are positive numbers, and y is larger than x.

In an embodiment, particle donor layer 104 comprises a metal nitride:MN_(x), and switching layer 106 comprises a metal nitride: MN_(y), wherey and x are positive numbers, and y is larger than x. In anotherembodiment, particle donor layer 104 comprises a metal oxide: MO_(X),and switching layer 106 comprises a metal oxide: MO_(y). In still otherembodiments, the metal compound of particle donor layer 104 is selectedfrom a first group consisting of: MN_(x) and MO_(x), and the switchinglayer is selected from a second group consisting of: SiN_(y) andSiO_(y), where y is a non-stoichiometric value.

FIG. 2 depicts block diagrams of example filament operation for atwo-terminal memory cell 200, according to one or more additionalembodiments. Memory cell 200 is depicted in two stages, includingfilament formation 210 stage and formed conductive filament 214 stage.Memory cell 200 comprises a top electrode 202, particle donor layer 204,switching layer 206 and bottom electrode 208 for each of the stages. Atfilament formation 210, a positive voltage is applied at top electrode202, V_(TE). Positive voltage at top electrode 202 generates an electricfield, which ionizes metal atoms or metal particles (e.g., groups ofmetal atoms) in particle donor layer 204, and causes diffusion of themetal ions into switching layer 206. In various embodiments, particledonor layer 204 can be selected to have a moderate material resistivity(e.g., between about 0.5 mohm-cm and about 100 mohm-cm), causing metalions to enter switching layer 206 in a relatively narrow band. Thisnarrow band of metal ions is depicted is referred to in the FIG. 2 asstimulus-induced particle drift 212. Once metal ions extend throughswitching layer 206 (or far enough through switching layer 206 for atunneling current to provide continuity between the filament and bottomelectrode 208), a conductive filament having electrical continuitythrough switching layer 206 is formed. This is depicted at formedconductive filament 214 state, as conductive particles spanning theswitching layer 218.

Once the conductive filament is formed, memory cell 200 has relativelyhigh electrical conductivity in a conductive state. The resistivity ofparticle donor layer 204, in combination with a small contact area 220of the conductive filament tend to result in a relatively narrowconduction path 216 through particle donor layer 204. In turn, thenarrow conduction path and resistivity of particle donor layer 204result in intrinsic current limiting characteristics. The currentlimiting characteristics can resist an increase in current throughmemory cell 200 after formation of the conductive filament (e.g., seeFIG. 5, infra). Accordingly, once programmed to the conducting state,memory cell 200 can resist damage from high current, by limiting theincrease in current through memory cell 200 for voltages above athreshold voltage (or a narrow threshold range of voltages).

FIG. 2A depicts block diagrams of example filament operation for analternative embodiment of the subject disclosure. In some embodiments,filament operation and memory cell of FIG. 2A can be in suitable part orin whole combined with filament operation/memory cell of FIG. 2. Inother embodiments, the memory cells/filament operations can be distinct.

FIG. 2A depicts a memory cell 200A comprising a top electrode 202Aoverlying a particle donor layer 204A, which in turn overlies aswitching layer 206A overlying a bottom electrode 208A. FIG. 2Aillustrates the filament operation in two stages, including a filamentformation 210A stage and a formed conductive filament 216A stage.Metal-containing particles 212A within particle donor layer 204A beginto drift within switching layer 206A in response to a bias (e.g.,positive bias) applied to top electrode 202A. The stimulus-inducedparticle drift 214A does not provide a continuous electrical connectionbetween particle donor layer 204A and bottom electrode 208A; accordinglyan electrical resistance of switching layer 206A dominates conductivityof memory cell 200A during filament formation 210A. In one or moreembodiments, particle donor layer 204A and particles 212A can becomprised of a metal nitride MN_(x) (e.g., AlN_(x) or other suitablemetal nitride, where M is a metal) where x is a first positive numberproviding a non-stoichiometric relationship of Al and N. In at least oneembodiment, switching layer 206A can additionally comprise a metalnitride MN_(y) (e.g., AlN_(y) or other suitable metal nitride, wherey>x). The metal utilized for switching layer 206A can be the same metalused for particle donor layer 204A in some embodiments, whereas in otherembodiments different metals can be employed.

During formed conductive filament 216A stage, the positive biascontinues to drive particles 212A into switching layer 206A untilconductive particles span the switching layer 206A, forming a conductivefilament 218A. Particles 202A leaving particle donor layer 204A canleave a localized particle depletion region 220A, having higherelectrical resistance than surrounding localities of particle donorlayer 204A. The increased resistance in this localized particledepletion region 220A can mitigate an increase or spike in currentthrough memory device 200A upon caused by completion of conductivefilament 218A, and more particularly the completion (e.g., which can beabrupt) of electrical continuity of conductive filament 218A. Bymitigating the increase in current, conductive filament 218A cancomplete continuity without driving large numbers of particles 212A intoswitching layer 206A, thereby maintaining a relatively thin conductivefilament 218A and relatively small contact area 222A.

FIG. 3 depicts a block diagram of an example filament deformation 300 ofa conductive filament within a disclosed two-terminal memory cell,according to one or more additional embodiments. The two-terminal memorycell comprises a top electrode 302, particle donor layer 304, switchinglayer 306 and bottom electrode 308 (e.g., similar to that describedabove at FIG. 2, supra). A reverse bias 310 is applied to the memorycell, of opposite polarity as a program bias used to form a conductivefilament within the memory cell. In response to reverse bias 310, ionswithin switching layer 306 can be mobilized (e.g., removed from defectlocations) and drift back toward particle donor layer 304. This breakscontinuity of a conductive filament formed by the ions, restoring a highresistance state for the two-terminal memory device. As depicted, theions that drift back toward particle donor layer 304 can re-enter theparticle donor layer 304, or aggregate near a boundary of switchinglayer 306 and particle donor layer 304.

FIG. 4 illustrates a block diagram of an alternative two-terminal memorycell 400, according to other disclosed embodiments. Memory cell 400 cancomprise a top electrode 402, electrically-resistive switching layer404, a stable resistive layer 406 and a bottom electrode 408. In theembodiment of memory cell 400, top electrode 402 can be a particle donorlayer, and comprise metal atoms that can be ionized and drift intoswitching layer 404 in response to a suitable electric field applied tomemory cell 400. According to this embodiment, top electrode can becomprised of a noble metal, Ag, Al, Cu, Pt, Pd, and others. Switchinglayer 404 can be a Si-bearing material, solid electrolyte, metal oxide,metal nitride, etc., having defect locations to trap metal particleswithin switching layer 404, in the absence of a suitable mobilizingstimulus. Additionally, stable resistive layer 406 can have a moderatematerial resistivity, e.g., between about 0.5 mohm-cm and about 100mohm-cm. Stable resistive layer 406 can provide a minimum electricalresistance for memory cell 400, when a conductive filament is formedwithin switching layer 404 and the memory cell is in a conductive state.This electrical resistance can be selected to provide a reducedoperating current for memory cell 400 in the conductive state. Thestable resistive layer 406 can be composed of SiNx, TaNy or WNz where x,y and z are positive numbers selected to produce compounds havingresistivity between about 0.5 mohm-cm to about 100 mohm-cm.

FIG. 5 illustrates block diagrams of an example filament formation fortwo-terminal memory cell 400 of FIG. 4, supra, referred to as memorycell 500 in the following description. Memory cell 500 is illustrated intwo stages, including a filament formation 500A stage and a formedconductive filament 500B stage. Memory cell 500 comprises a topelectrode 502 overlying an electrically-resistive switching layer 504,which overlies a stable resistive layer 506, which in turn overlies abottom electrode 508. At filament formation 500A, a positive voltageV_(P) is applied at top electrode 502. In some embodiments, V_(P) can bethe same or substantially the same as V_(TE) applied to memory cell 200of FIG. 2, supra. In other embodiments, V_(P) can have a differentmagnitude from V_(TE), depending on materials utilized for top electrode502, electrically-resistive switching layer 504, stable resistive layer506 or bottom electrode 508 (e.g., as compared with materials employedfor memory cell 200), or depending on resistivity or resistance ofelectrically-resistive switching layer 504 or stable resistive layer 506(e.g., as compared with resistivity or resistance of particle donorlayer 204 and switching layer 206), or other factors associated with aprogram threshold voltage of memory cell 500.

The positive voltage V_(P) applied at top electrode 502 generates anelectric field, which ionizes metal atoms or metal particles in topelectrode 502. Top electrode 502 can be a suitable particle donor layercomprising Ag, Al, Cu, Pt, Pd, and others (optionally in conjunctionwith a barrier material or an adhesion material, including Ti, TiN, TaN,TiW, or the like, below or above top electrode 502). Top electrode 502can be comprised of a pure or substantially pure composition of theforegoing metals, as one example, having low resistivity (e.g., 0.02mohm-cm or less) in some embodiments. Electrically-resistive switchinglayer 504 can have a high material resistivity that is, for instance,several orders of magnitude greater than the low resistivity of topelectrode 502. During filament formation 500A, stimulus-induced particledrift 510A occurs within electrically-resistive switching layer 504, inwhich particles of top electrode 502 enter electrically-resistiveswitching layer 504 but do not (yet) provide electrical continuitybetween top electrode 502 and stable resistive layer 506. Therefore,during filament formation 500A, the electrical resistance ofelectrically-resistive switching layer 504 dominates the resistance ofmemory cell 500.

A formed conductive filament 500B is depicted on the right side of FIG.5. Formed conductive filament 500B comprises conductive particlestraversing the switching layer 512B, providing electrical continuitybetween top electrode 502 and stable resistive layer 506. Because formedconductive filament 500B provides a conductive path through theelectrically-resistive switching layer 504, the electrical resistance ofstable resistive layer 506 becomes the dominant resistance of memorycell 500.

Once formed conductive filament 500B provides electrical continuitybetween top electrode 502 and stable resistive layer 506, the currentconducted by memory cell 500 increases significantly. In conventionalmemory devices, the increase in current following switching from a highresistance state to a low resistance state can drive a significantnumber of particles from a top electrode into a switching layer,resulting in a relatively thick conductive filament. Memory cell 500 canbe configured to mitigate or avoid formation of a thick conductivefilament, in various embodiments. For instance, a resistance orresistivity of stable resistive layer 506 can be selected to limit theincrease in current conducted by memory cell 500 following formation offormed conductive filament 500B. By keeping the increase in currentbelow a suitable threshold or within a suitable range, formed conductivefilament 500B can remain quite thin, having a small contact area 514Bwith stable resistive layer 506. The small contact area 514B can alsoact to limit current flow through memory cell 500, by maintaining asmall current cross-section and relatively narrow conduction path 510Bat stable resistive layer. In various embodiments, stable resistivelayer 506 can be selected to have a resistivity within a range of about0.5 mohm-cm and about 100 mohm-cm. In further embodiments, stableresistive layer 506 can be composed of SiNx, TaNy, WNz, or the like,where x, y and z are positive numbers selected to form silicon nitride,tantalum nitride and tungsten nitride compounds, respectively, withresistivity within a range of about 0.5 mohm-cm and about 100 mohm-cm.

FIG. 6 illustrates a block diagram of a sample filament deformation 600of a conductive filament within a disclosed two-terminal memory cell, invarious further embodiments. The two-terminal memory cell (e.g., aresistive-switching memory cell) comprises a top electrode 602, aswitching layer 604, a stable resistive layer 606 and a bottom electrode608. Top electrode 602 can be a particular donor layer, in variousembodiments, comprising a metal having relatively high surface energyand diffusivity (e.g., Ag, Cu, Al, Pt, Au, etc.) so as to be at least inpart permeable within switching layer 604. A reverse bias 610 applied tothe memory cell causes ions within switching layer 604 are mobilized(e.g., removed from defect locations within switching layer 604 thatwould otherwise suitable—at low or no bias potential—to hold the ions inplace) away from bottom electrode 608 and toward top electrode 602.Accordingly, ions or particles having created a conductive filamentthrough switching layer 604 drift toward top electrode 602, and breakelectrical continuity. This results in a deformed/non-continuousfilament 612 of particles within switching layer 604 or within topelectrode 602 (or partially within both switching layer 604 and topelectrode 602), that does not provide electrical continuity between topelectrode 602 and stable resistive layer 606.

FIG. 7 illustrates a diagram of an example current-voltage response 700(I-V response 700) for a memory cell according to the embodiment ofFIG. 1. It should be appreciated that I-V response 700 is merely anillustrative example, as current and voltage characteristics of memorycell 100 can vary for different selections of disclosed materials forvarious components of memory cell 100. In various embodiments, forinstance, a program voltage for memory cell 100 can vary from betweenabout 1 volt and about 3 volts, and can vary in different amounts orranges for other embodiments.

As an overview, I-V response 700 illustrates current on a vertical axisand voltage on a horizontal axis. Current ranges from 1.0 E-11 amps toabout 1.0 E-4 amps on a logarithmic scale. The horizontal voltage scaleranges from about +/−2.7 volts.

Initial bias 702 illustrates the I-V response of memory cell 100 in aresistive state. Current increases relatively slowly from 1.0 E-11 ampsto about 1.0 E-8 amps over a range of zero volts to just over 1.5 volts,representing leakage current through the memory cell in its resistivestate. At about 1.6 volts, filament formation 704 is initiated, whereconductive particles drift into a switching layer of memory cell 100 andrapidly decrease electrical resistance of the memory cell. In variousembodiments, filament formation 704—beginning at initiation of particledrift and completing with electrical continuity through the switchinglayer—can be very rapid, occurring in only a few nanoseconds in at leastone embodiment. During filament formation 704, current increases rapidlyfrom about 1.0 E-8 amps to about 2 E-5 amps over a couple tenths of avolt. This provides significant sensing margin for voltages above about1.8 volts versus voltages below about 1.6 volts. Above about 1.8 volts,filament completion occurs and innate current restriction 706 isobserved, where memory cell 100 has a much slower increase in current inresponse to increasing voltage. Current increases only about 20 to 30microamps from about 1.8 volts to about 2.5 volts. Thus, at voltagesgreater than about 1.8 volts, memory cell 100 has a significantintrinsic restriction on current flow, protecting memory cell 100 fromcurrent spikes associated with large bandwidth memory operations (e.g.,an operation having sufficient current to program hundreds of thousandsof memory cells, as one example).

Memory cell 100 can be configured to be a reversibly programmabledevice. When in a conductive state, application of a reverse bias 708ionizes metal particles of a conductive filament, and applies a forcethat pushes metal particles toward a particle donor layer. At filamentdiscontinuity 710, electrical discontinuity of a conductive path formedby the conductive filament begins, causing the memory cell to be in anon-conductive state (e.g., see FIG. 3, supra). Filament discontinuity710 can also be quite rapid, taking only a few nanoseconds or tens ofnanoseconds, and resulting in multiple orders of magnitude reduction incurrent over about 100 millvolts.

FIG. 8 illustrates a block diagram of an example 1T-nR memoryarchitecture 800 according to alternative or additional embodiments ofthe present disclosure. Memory architecture 800 comprises a substrate802 comprising one or more CMOS devices 804 formed thereon or therein.Additionally, a set of select transistors 806 are formed on substrate802. Select transistors 806 (including select transistors 806A, 806B)can be respectively connected to a number, n, of two-terminal memorycells, and activate or deactivate the two-terminal memory cells byconnecting electrical power (e.g., a program signal, a read signal) orsensing circuits to the memory cells.

One or more insulator 807 layer(s) are formed over substrate 802 inconjunction with backend-of-line devices (e.g., metal lines, vias,vertical interconnects, memory arrays, and so on). A first via layer,via₁ 808 connects select transistor 806A to a first bitline, bitline₁810. A set of non-volatile memory cells 812 are formed on bitline₁ 810and respectively connected to different wordlines of a set of wordlines818. In some embodiments, non-volatile memory cells 812 can comprise amemory component 814 (e.g., memory cell 100, memory cell 400, etc.) inelectrical series with a selector component 816. In one or moreembodiments, selector component 816 can be a Crossbar FAST™ device,provided by the assignee of the present disclosure (e.g., see co-pendingU.S. patent application Ser. No. 14/588,185 entitled SELECTOR DEVICE FORTWO-TERMINAL MEMORY and filed Dec. 31, 2014, incorporated by referenceherein in its entirety and for all purposes).

In some embodiments, a second set of non-volatile memory cells 812 canbe formed above respective ones of wordlines 818 and connected to asecond bitline, bitline₂ 820. Bitline₂ 820 can then be connected to asecond select transistor, such as select transistor 806B. In theembodiments depicted by memory architecture 800, the connection can beaccomplished by three via layers, including via₁ layer 808, a second vialayer, via₂ layer 822 and a third via layer, via₃ layer 824.

Example Methods for Implementing Disclosed Embodiments

The diagrams included herein are described with respect to interactionbetween several layers of a memory cell, or memory cells in a memoryarchitectures. It should be appreciated that such diagrams can includethose layers specified therein, some of the specified layers, oradditional layers (e.g., a barrier layer, a diffusion-mitigation layer,etc.). Sub-components of disclosed memory architectures can also beimplemented as electrically connected to other sub-components ratherthan included within a parent architecture. Additionally, it is notedthat one or more disclosed processes can be combined into a singleprocess providing aggregate functionality. For instance, a programprocess can comprise an erase process, or vice versa, to facilitateprogramming and erasing a semiconductor cell by way of a single process.In addition, it should be appreciated that respective rows of multiplecell memory architectures can be erased in groups (e.g., multiple rowserased concurrently) or individually. Moreover, it should be appreciatedthat multiple memory cells on a particular row can be programmed ingroups (e.g., multiple memory cells programmed concurrently) orindividually. Components of the disclosed architectures can alsointeract with one or more other components not specifically describedherein but known by those of skill in the art.

In view of the exemplary diagrams described supra, process methods thatcan be implemented in accordance with the disclosed subject matter willbe better appreciated with reference to the flow charts of FIGS. 9-11.While for purposes of simplicity of explanation, the methods of FIGS.9-11 are shown and described as a series of blocks, it is to beunderstood and appreciated that the claimed subject matter is notlimited by the order of the blocks, as some blocks may occur indifferent orders and/or concurrently with other blocks from what isdepicted and described herein. Moreover, not all illustrated blocks maybe required to implement the methods described herein. Additionally, itshould be further appreciated that the methods disclosed throughout thisspecification are capable of being stored on an article of manufactureto facilitate transporting and transferring such methodologies to anelectronic device. The term article of manufacture, as used, is intendedto encompass a computer program accessible from any computer-readabledevice, device in conjunction with a carrier, or storage medium.

FIG. 9 depicts a flowchart of an example method 900 for fabricating amemory cell according to alternative or additional embodiments of thepresent disclosure. At 902, method 900 can comprise providing a bottomelectrode over a semiconductor substrate comprising a CMOS device. Invarious embodiments, the bottom electrode can be a conductive material,such as TiN, TaN, W, WN, TiW, or a suitable alloy of the foregoing. Inother embodiments, the bottom electrode can be a conductive silicon(e.g., a polycrystalline SiGe, a doped polycrystalline SiGe, apolysilicon, a doped polysilicon, etc.).

At 904, method 900 can comprise providing an electrically-resistiveswitching layer over the bottom electrode. In some embodiments, theswitching layer can have greater than 0.5 ohm-cm material resistivity.Further, the switching layer can be at least in part porous toconductive particles (e.g., metal ions, oxygen vacancies, etc.). Theswitching layer can further comprise defect sites therein (e.g., silicondangling bonds, vacancies, voids, etc.) in which the conductiveparticles can become trapped in the absence of a suitably strongexternal stimulus. In some embodiments, the switching layer can becomprised of a Si-bearing material, a solid electrolyte, a metal oxide,a metal nitride, or the like. In one or more embodiments, the switchinglayer can comprise a material selected from the group consisting of:SiO_(y), AlN_(y), TiO_(y), TaO_(y), AlO_(y), CuO_(y), SiN_(x), TiN_(X),TiN_(y), TaN_(x), TaN_(y), SiO_(x), AlN_(x), CuN_(x), CuN_(y), AgN_(x),AgN_(y), TiO_(x), TaO_(x), AlO_(x), CuO_(x), AgO_(x), and AgO_(y), wherex and y are positive numbers, and y is larger than x.

At 906, method 900 can comprise providing a particle donor layer havinga second material resistivity, over the electrically-resistive switchinglayer. The second material resistivity can be in a range between about0.5 mohm-cm and about 100 mohm-cm. In various embodiments, the particledonor layer can be selected to have a second material resistivity inproportion to a first material resistivity of the switching layer. Insome embodiments, the proportion can be about 1:5; in other embodimentsthe proportion can be about 1:1000; whereas in still other embodimentsthe proportion can be selected from a range between about 1:5 and about1:1000. In further embodiments, the proportion of second materialresistivity of the particle donor layer to the first materialresistivity of the switching layer can be larger than 1:1000 (e.g.,1:5000, 1:10,000, 1:100,000, etc.). In further embodiments, the particledonor layer can comprise a metal nitride selected from the groupconsisting of: TiN_(X), TaN_(x), AlN_(x), CuN_(x), WN_(x) and AgN_(x),where x is a positive number. In other embodiments, the particle donorlayer can comprise a metal oxide selected from the group consisting of:TiO_(x), Tao_(x), AlO_(x), CuO_(x), WO_(x) and AgO_(x). In yet otherembodiments, the particle donor layer can comprise a metal oxi-nitrideselected from the group consisting of: TiO_(a)N_(b), AlO_(a)N_(b),CuO_(a)N_(b), WO_(a)N_(b) and AgO_(a)N_(b), where a and b are positivenumbers. In at least one embodiment, the switching layer can be providedwith a metal nitride MN_(y) and the particle donor layer can be providedwith a metal nitride MN_(x), where y is larger than x. In a furtherembodiment, the switching layer can be provided with a metal oxideMO_(y) and the particle donor layer can be provided with a metal oxideMO_(x). In yet another embodiment, the particle donor layer can beprovided with a metal compound selected from a first group consisting ofMN_(x) and MO_(x), and the switching layer can be provided with asilicon compound selected from a second group consisting of: SiN_(y) andSiO_(y), where y is a non-stoichiometric value.

At 908, method 900 can comprise providing a contact layer over theconductive particle donor layer. The contact layer can be a topelectrode, in some embodiments. For instance, the contact layer cancomprise a metal wire of a memory array, a conductive plug thatelectrically connects the particle donor layer to the metal wire of thememory array, or the like. The contact layer can be formed of a suitableelectrical conductor, such as a metal (e.g., Al, Cu, Ag, and so forth inconjunction with optional barrier material or adhesion material,including Ti, TiN, TaN, TiW, or the like, below or above the conductorlayer), a conductive silicon (e.g., doped polysilicon, dopedpolycrystalline SiGe, etc.), or the like.

FIG. 10 depicts a flowchart of a sample method 1000 for fabricating amemory cell according to further embodiments. At 1002, method 1000 cancomprise providing a substrate for an electronic device. At 1004, method1000 can comprise forming a bottom electrode of a memory device over thesubstrate. At 1006, method 1000 can comprise forming a switching layerover the bottom electrode, and at 1008, method 1000 can comprise forminga particle donor layer with moderate resistivity over the switchinglayer. In various embodiments, the particle donor layer can have aresistivity between about 0.5 mohm-cm and about 100 mohm-cm. In afurther embodiment, the particle donor layer can have an electricalresistance between about 1 kilo-ohms and about 100 kilo-ohms. At 1010,method 1000 can comprise forming a top electrode layer over the particledonor layer. At 1012, method 1000 can comprise forming a second memorydevice sharing the top electrode or bottom electrode, and forming one ormore additional memory devices, up to a suitable number n (where n canbe, e.g., 128, 256, 512, 1024, 2048, etc.) of memory devices sharing thetop electrode or the bottom electrode. At 1014, method 1000 can compriseconnecting the shared top electrode or bottom electrode to a selecttransistor.

FIG. 11 illustrates a flowchart of a sample method 1100 for fabricatinga memory device according to alternative or additional embodiments ofthe present disclosure. At 1102, method 1100 can comprise providing abottom electrode over a semiconductor substrate comprising a CMOSdevice. The bottom electrode can comprise any suitable conductivematerial described herein or known in the art. At 1104, method 1100 cancomprise providing a stable resistive layer overlying the bottomelectrode. The stable resistive layer can be fabricated so as to have aresistivity between about 0.5 mohm-cm and about 100 mohm-cm, in someembodiments. In some embodiments, the stable resistive layer can becomposed of SiN_(x), TaN_(y) or WN_(z) where x, y and z are positivenumbers selected to produce compounds having resistivity between about0.5 mohm-cm and about 100 mohm-cm. At 1106, method 1100 can compriseproviding an electrically-resistive switching layer overlying the stableresistive layer. The electrically-resistive switching layer can havemuch larger resistivity. As one example, the electrically-resistiveswitching layer can have a resistivity greater than about 500 mohm-cm.The electrically-resistive switching layer can be a silicon bearingmaterial, in some embodiments, a solid electrolyte, a metal oxide, ametal nitride, or other suitable material described herein or known inthe art. At 1108, method 1100 can comprise providing a particle donorlayer overlying the electrically-resistive switching layer. The particledonor layer can be a metal, such as Ag, Al, Cu, Pt, Pd, and others, orcan be comprised of such a metal. At 1110, method 1100 can compriseforming a contact layer over the particle donor layer. The contact layercan be a metal wire of a memory array (e.g., a bitline, a wordline, asourceline, a dataline, etc.), or can be a metal plug providingelectrical continuity between the particle donor layer and such a metalwire, as one example.

Example Operating Environments

In various embodiments of the subject disclosure, disclosed memory ormemory architectures can be employed as a standalone or integratedembedded memory device with a CPU or microcomputer. Some embodiments canbe implemented, for instance, as part of a computer memory (e.g., randomaccess memory, cache memory, read-only memory, storage memory, or thelike). Other embodiments can be implemented, for instance, as a portablememory device. Examples of suitable portable memory devices can includeremovable memory, such as a secure digital (SD) card, a universal serialbus (USB) memory stick, a compact flash (CF) card, or the like, orsuitable combinations of the foregoing.

In order to provide a context for the various aspects of the disclosedsubject matter, FIG. 12, as well as the following discussion, isintended to provide a brief, general description of a suitableenvironment in which various aspects of the disclosed subject matter canbe implemented or processed. While the subject matter has been describedabove in the general context of electronic memory or architectures andprocess methods for fabricating such memory or architectures, thoseskilled in the art will recognize that the subject disclosure also canbe implemented in combination with other architectures or processmethods. Moreover, those skilled in the art will appreciate that thedisclosed processes can be practiced with a processing system or acomputer processor, either alone or in conjunction with a host computer(e.g., computer 1302 of FIG. 13, infra), which can includesingle-processor or multiprocessor computer systems, mini-computingdevices, mainframe computers, as well as personal computers, hand-heldcomputing devices (e.g., PDA, smart phone, watch), microprocessor-basedor programmable consumer or industrial electronics, and the like. Theillustrated aspects may also be practiced in distributed computingenvironments where tasks are performed by remote processing devices thatare linked through a communications network. However, some, if not allaspects of the subject innovation can be practiced on stand-aloneelectronic devices, such as a memory card, Flash memory module,removable memory, or the like. In a distributed computing environment,program modules can be located in both local and remote memory storagemodules or devices.

FIG. 12 illustrates a block diagram of an example operating and controlenvironment 1200 for a memory bank 1202 of a multi-bank memory cellarray according to aspects of the subject disclosure. In at least oneaspect of the subject disclosure, memory bank 1202 can comprise memoryselected from a variety of memory cell technologies. In at least oneembodiment, memory bank 1202 can comprise a two-terminal memorytechnology, arranged in a compact two or three dimensional architecture.Suitable two-terminal memory technologies can includeresistive-switching memory, conductive-bridging memory, phase-changememory, organic memory, magneto-resistive memory, or the like, or asuitable combination of the foregoing.

A column controller 1206 and sense amps 1208 can be formed adjacent tomemory bank 1202. Moreover, column controller 1206 can be configured toactivate (or identify for activation) a subset of bitlines of memorybank 1202. Column controller 1206 can utilize a control signal providedby a reference and control signal generator(s) 1218 to activate, as wellas operate upon, respective ones of the subset of bitlines, applyingsuitable program, erase or read voltages to those bitlines.Non-activated bitlines can be kept at an inhibit voltage (also appliedby reference and control signal generator(s) 1218), to mitigate or avoidbit-disturb effects on these non-activated bitlines.

In addition, operating and control environment 1200 can comprise a rowcontroller 1204. Row controller 1204 can be formed adjacent to andelectrically connected with word lines of memory bank 1202. Further,utilizing control signals of reference and control signal generator(s)1218, row controller 1204 can select particular rows of memory cellswith a suitable selection voltage. Moreover, row controller 1204 canfacilitate program, erase or read operations by applying suitablevoltages at selected word lines.

Sense amps 1208 can read data from, or write data to the activatedmemory cells of memory bank 1202, which are selected by column control1206 and row control 1204. Data read out from memory bank 1202 can beprovided to an input and input/output buffer 1212 (e.g., an LPDDRbuffer, in some embodiments). Likewise, data to be written to memorybank 1202 can be received from the input and input/output buffer 1212and written to the activated memory cells of memory bank 1202.

A clock source(s) 1210 can provide respective clock pulses to facilitatetiming for read, write, and program operations of row controller 1204and column controller 1206. Clock source(s) 1210 can further facilitateselection of wordlines or bitlines in response to external or internalcommands received by operating and control environment 1200. Input andinput/output buffer 1212 can comprise a command and address input, aswell as a bidirectional data input and output. Instructions are providedover the command and address input, and the data to be written to memorybank 1202 as well as data read from memory bank 1202 is conveyed on thebidirectional data input and output, facilitating connection to anexternal host apparatus, such as a computer or other processing device(not depicted, but see e.g., computer 1302 of FIG. 13, infra).

Input and input/output buffer 1212 can be configured to receive writedata, receive an erase instruction, receive a status or maintenanceinstruction, output readout data, output status information, and receiveaddress data and command data, as well as address data for respectiveinstructions. Address data can be transferred to row controller 1204 andcolumn controller 1206 by an address register 1210. In addition, inputdata is transmitted to memory bank 1202 via signal input lines betweensense amps 1208 and input and input/output buffer 1212, and output datais received from memory bank 1202 via signal output lines from senseamps 1208 to input and input/output buffer 1212. Input data can bereceived from the host apparatus, and output data can be delivered tothe host apparatus via the I/0 bus.

Commands received from the host apparatus can be provided to a commandinterface 1216. Command interface 1216 can be configured to receiveexternal control signals from the host apparatus, and determine whetherdata input to the input and input/output buffer 1212 is write data, acommand, or an address. Input commands can be transferred to a statemachine 1220.

State machine 1220 can be configured to manage programming andreprogramming of memory bank 1202 (as well as other memory banks of themulti-bank memory array). Instructions provided to state machine 1220are implemented according to control logic configurations, enablingstate machine 1220 to manage read, write, erase, data input, dataoutput, and other functionality associated with memory bank 1202. Insome aspects, state machine 1220 can send and receive acknowledgmentsand negative acknowledgments regarding successful receipt or executionof various commands. In further embodiments, state machine 1220 candecode and implement status-related commands, decode and implementconfiguration commands, and so on.

To implement read, write, erase, input, output, etc., functionality,state machine 1220 can control clock source(s) 1208 or reference andcontrol signal generator(s) 1218. Control of clock source(s) 1208 cancause output pulses configured to facilitate row controller 1204 andcolumn controller 1206 implementing the particular functionality. Outputpulses can be transferred to selected bitlines by column controller1206, for instance, or wordlines by row controller 1204, for instance.

The illustrated aspects of the disclosure may also be practiced indistributed computing environments where certain tasks are performed byremote processing devices that are linked through a communicationsnetwork. In a distributed computing environment, program modules orstored information, instructions, or the like can be located in local orremote memory storage devices.

Moreover, it is to be appreciated that various components describedherein can include electrical circuit(s) that can include components andcircuitry elements of suitable value in order to implement theembodiments of the subject innovation(s). Furthermore, it can beappreciated that many of the various components can be implemented onone or more IC chips. For example, in one embodiment, a set ofcomponents can be implemented in a single IC chip. In other embodiments,one or more of respective components are fabricated or implemented onseparate IC chips.

In connection with FIG. 13, the systems and processes described belowcan be embodied within hardware, such as a single integrated circuit(IC) chip, multiple ICs, an application specific integrated circuit(ASIC), separate devices interconnected by one or more input/outputinterfaces or communication devices, or the like. Further, the order inwhich some or all of the process blocks appear in each process shouldnot be deemed limiting. Rather, it should be understood that some of theprocess blocks can be executed in a variety of orders, not all of whichmay be explicitly illustrated herein.

With reference to FIG. 13, a suitable environment 1300 for implementingvarious aspects of the claimed subject matter includes a computer 1302.The computer 1302 includes a processing unit 1304, a system memory 1306,a codec 1335, and a system bus 1308. The system bus 1308 couples systemcomponents including, but not limited to, the system memory 1306 to theprocessing unit 1304. The processing unit 1304 can be any of variousavailable processors. Dual microprocessors and other multiprocessorarchitectures also can be employed as the processing unit 1304.

The system bus 1308 can be any of several types of bus structure(s)including the memory bus or memory controller, a peripheral bus orexternal bus, and/or a local bus using any variety of available busarchitectures including, but not limited to, Industrial StandardArchitecture (ISA), Micro-Channel Architecture (MSA), Extended ISA(EISA), Intelligent Drive Electronics (IDE), VESA Local Bus (VLB),Peripheral Component Interconnect (PCI), Card Bus, Universal Serial Bus(USB), Advanced Graphics Port (AGP), Personal Computer Memory CardInternational Association bus (PCMCIA), Firewire (IEEE 1394), and SmallComputer Systems Interface (SCSI).

The system memory 1306 includes volatile memory 1310 and non-volatilememory 1312. The basic input/output system (BIOS), containing the basicroutines to transfer information between elements within the computer1302, such as during start-up, is stored in non-volatile memory 1312. Inaddition, according to present innovations, codec 1335 may include atleast one of an encoder or decoder, wherein the at least one of anencoder or decoder may consist of hardware, software, or a combinationof hardware and software. Although, codec 1335 is depicted as a separatecomponent, codec 1335 may be contained within non-volatile memory 1312.By way of illustration, and not limitation, non-volatile memory 1312 caninclude read only memory (ROM), programmable ROM (PROM), electricallyprogrammable ROM (EPROM), electrically erasable programmable ROM(EEPROM), or flash memory. Volatile memory 1310 includes random accessmemory (RAM), which acts as external cache memory. According to presentaspects, the volatile memory may store the write operation retry logic(not shown in FIG. 13) and the like. By way of illustration and notlimitation, RAM is available in many forms such as static RAM (SRAM),dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM(DDR SDRAM), and enhanced SDRAM (ESDRAM), among others.

Computer 1302 may also include removable/non-removable,volatile/non-volatile computer storage medium. FIG. 13 illustrates, forexample, disk storage 1314. Disk storage 1314 includes, but is notlimited to, devices like a magnetic disk drive, solid state disk (SSD)floppy disk drive, tape drive, Jaz drive, Zip drive, LS-100 drive, flashmemory card, or memory stick. In addition, disk storage 1314 can includestorage medium separately or in combination with other storage mediumincluding, but not limited to, an optical disk drive such as a compactdisk ROM device (CD-ROM), CD recordable drive (CD-R Drive), CDrewritable drive (CD-RW Drive) or a digital versatile disk ROM drive(DVD-ROM). To facilitate connection of the disk storage devices 1314 tothe system bus 1308, a removable or non-removable interface is typicallyused, such as interface 1316. It is appreciated that storage devices1314 can store information related to a user. Such information might bestored at or provided to a server or to an application running on a userdevice. In one embodiment, the user can be notified (e.g., by way ofoutput device(s) 1336) of the types of information that are stored todisk storage 1314 and/or transmitted to the server or application. Theuser can be provided the opportunity to opt-in or opt-out of having suchinformation collected and/or shared with the server or application e.g.,by way of input from input device(s) 1328).

It is to be appreciated that FIG. 13 describes software that acts as anintermediary between users and the basic computer resources described inthe suitable operating environment 1300. Such software includes anoperating system 1318. Operating system 1318, which can be stored ondisk storage 1314, acts to control and allocate resources of thecomputer system 1302. Applications 1320 take advantage of the managementof resources by operating system 1318 through program modules 1324, andprogram data 1326, such as the boot/shutdown transaction table and thelike, stored either in system memory 1306 or on disk storage 1314. It isto be appreciated that the claimed subject matter can be implementedwith various operating systems or combinations of operating systems.

A user enters commands or information into the computer 1302 throughinput device(s) 1328. Input devices 1328 include, but are not limitedto, a pointing device such as a mouse, trackball, stylus, touch pad,keyboard, microphone, joystick, game pad, satellite dish, scanner, TVtuner card, digital camera, digital video camera, web camera, and thelike. These and other input devices connect to the processing unit 1304through the system bus 1308 via interface port(s) 1330. Interfaceport(s) 1330 include, for example, a serial port, a parallel port, agame port, and a universal serial bus (USB). Output device(s) 1336 usesome of the same type of ports as input device(s) 1328. Thus, forexample, a USB port may be used to provide input to computer 1302 and tooutput information from computer 1302 to an output device 1336. Outputadapter 1334 is provided to illustrate that there are some outputdevices 1336 like monitors, speakers, and printers, among other outputdevices 1336, which require special adapters. The output adapters 1334include, by way of illustration and not limitation, video and soundcards that provide a means of connection between the output device 1336and the system bus 1308. It should be noted that other devices and/orsystems of devices provide both input and output capabilities such asremote computer(s) 1338.

Computer 1302 can operate in a networked environment using logicalconnections to one or more remote computers, such as remote computer(s)1338. The remote computer(s) 1338 can be a personal computer, a server,a router, a network PC, a workstation, a microprocessor based appliance,a peer device, a smart phone, a tablet, or other network node, andtypically includes many of the elements described relative to computer1302. For purposes of brevity, only a memory storage device 1340 isillustrated with remote computer(s) 1338. Remote computer(s) 1338 islogically connected to computer 1302 through a network interface 1342and then connected via communication connection(s) 1344. Networkinterface 1342 encompasses wire and/or wireless communication networkssuch as local-area networks (LAN) and wide-area networks (WAN) andcellular networks. LAN technologies include Fiber Distributed DataInterface (FDDI), Copper Distributed Data Interface (CDDI), Ethernet,Token Ring and the like. WAN technologies include, but are not limitedto, point-to-point links, circuit switching networks like IntegratedServices Digital Networks (ISDN) and variations thereon, packetswitching networks, and Digital Subscriber Lines (DSL).

Communication connection(s) 1344 refers to the hardware/softwareemployed to connect the network interface 1342 to the bus 1308. Whilecommunication connection 1344 is shown for illustrative clarity insidecomputer 1302, it can also be external to computer 1302. Thehardware/software necessary for connection to the network interface 1342includes, for exemplary purposes only, internal and externaltechnologies such as, modems including regular telephone grade modems,cable modems and DSL modems, ISDN adapters, and wired and wirelessEthernet cards, hubs, and routers.

As utilized herein, terms “component,” “system,” “architecture” and thelike are intended to refer to a computer or electronic-related entity,either hardware, a combination of hardware and software, software (e.g.,in execution), or firmware. For example, a component can be one or moretransistors, a memory cell, an arrangement of transistors or memorycells, a gate array, a programmable gate array, an application specificintegrated circuit, a controller, a processor, a process running on theprocessor, an object, executable, program or application accessing orinterfacing with semiconductor memory, a computer, or the like, or asuitable combination thereof. The component can include erasableprogramming (e.g., process instructions at least in part stored inerasable memory) or hard programming (e.g., process instructions burnedinto non-erasable memory at manufacture).

By way of illustration, both a process executed from memory and theprocessor can be a component. As another example, an architecture caninclude an arrangement of electronic hardware (e.g., parallel or serialtransistors or memory cells), processing instructions and a processor,which implement the processing instructions in a manner suitable to thearrangement of electronic hardware. In addition, an architecture caninclude a single component (e.g., a transistor, a gate array, . . . ) oran arrangement of components (e.g., a series or parallel arrangement oftransistors, a gate array connected with program circuitry, power leads,electrical ground, input signal lines and output signal lines, and soon). A system can include one or more components as well as one or morearchitectures. It is to be appreciated that some overlap in definitionsis anticipated, and an architecture or a system can be a stand-alonecomponent, or a component of another architecture, system, etc.

In addition to the foregoing, the disclosed subject matter can beimplemented as a method, apparatus, or article of manufacture usingtypical manufacturing, programming or engineering techniques to producehardware, firmware, software, or any suitable combination thereof tocontrol an electronic device to implement the disclosed subject matter.The terms “apparatus” and “article of manufacture” where used herein areintended to encompass an electronic device, a semiconductor device, acomputer, or a computer program accessible from any computer-readabledevice, carrier, or media. Computer-readable media can include hardwaremedia, or software media. In addition, the media can includenon-transitory media, or transport media. In one example, non-transitorymedia can include computer readable hardware media. Specific examples ofcomputer readable hardware media can include but are not limited tomagnetic storage devices (e.g., hard disk, floppy disk, magnetic strips. . . ), optical disks (e.g., compact disk (CD), digital versatile disk(DVD) . . . ), smart cards, and flash memory devices (e.g., card, stick,key drive . . . ). Computer-readable transport media can include carrierwaves, or the like. Of course, those skilled in the art will recognizemany modifications can be made to this configuration without departingfrom the scope or spirit of the disclosed subject matter.

What has been described above includes examples of the subjectinnovation. It is, of course, not possible to describe every conceivablecombination of components or methodologies for purposes of describingthe subject innovation, but one of ordinary skill in the art canrecognize that many further combinations and permutations of the subjectinnovation are possible. Accordingly, the disclosed subject matter isintended to embrace all such alterations, modifications and variationsthat fall within the spirit and scope of the disclosure. Furthermore, tothe extent that a term “includes”, “including”, “has” or “having” andvariants thereof is used in either the detailed description or theclaims, such term is intended to be inclusive in a manner similar to theterm “comprising” as “comprising” is interpreted when employed as atransitional word in a claim.

Moreover, the word “exemplary” is used herein to mean serving as anexample, instance, or illustration. Any aspect or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other aspects or designs. Rather, use of the wordexemplary is intended to present concepts in a concrete fashion. As usedin this application, the term “or” is intended to mean an inclusive “or”rather than an exclusive “or”. That is, unless specified otherwise, orclear from context, “X employs A or B” is intended to mean any of thenatural inclusive permutations. That is, if X employs A; X employs B; orX employs both A and B, then “X employs A or B” is satisfied under anyof the foregoing instances. In addition, the articles “a” and “an” asused in this application and the appended claims should generally beconstrued to mean “one or more” unless specified otherwise or clear fromcontext to be directed to a singular form.

Additionally, some portions of the detailed description have beenpresented in terms of algorithms or process operations on data bitswithin electronic memory. These process descriptions or representationsare mechanisms employed by those cognizant in the art to effectivelyconvey the substance of their work to others equally skilled. A processis here, generally, conceived to be a self-consistent sequence of actsleading to a desired result. The acts are those requiring physicalmanipulations of physical quantities. Typically, though not necessarily,these quantities take the form of electrical and/or magnetic signalscapable of being stored, transferred, combined, compared, and/orotherwise manipulated.

It has proven convenient, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like. It should be borne in mind, however, thatall of these and similar terms are to be associated with the appropriatephysical quantities and are merely convenient labels applied to thesequantities. Unless specifically stated otherwise or apparent from theforegoing discussion, it is appreciated that throughout the disclosedsubject matter, discussions utilizing terms such as processing,computing, replicating, mimicking, determining, or transmitting, and thelike, refer to the action and processes of processing systems, and/orsimilar consumer or industrial electronic devices or machines, thatmanipulate or transform data or signals represented as physical(electrical or electronic) quantities within the circuits, registers ormemories of the electronic device(s), into other data or signalssimilarly represented as physical quantities within the machine orcomputer system memories or registers or other such information storage,transmission and/or display devices.

In regard to the various functions performed by the above describedcomponents, architectures, circuits, processes and the like, the terms(including a reference to a “means”) used to describe such componentsare intended to correspond, unless otherwise indicated, to any componentwhich performs the specified function of the described component (e.g.,a functional equivalent), even though not structurally equivalent to thedisclosed structure, which performs the function in the hereinillustrated exemplary aspects of the embodiments. In addition, while aparticular feature may have been disclosed with respect to only one ofseveral implementations, such feature may be combined with one or moreother features of the other implementations as may be desired andadvantageous for any given or particular application. It will also berecognized that the embodiments include a system as well as acomputer-readable medium having computer-executable instructions forperforming the acts and/or events of the various processes.

What is claimed is:
 1. A non-volatile memory cell, comprising: a bottomelectrode; an electrically-resistive switching layer above the bottomelectrode that is at least in part permeable to movement ofcurrent-carrying particles within the electrically-resistive switchinglayer; a particle donor layer above the electrically-resistive switchinglayer that provides the current-carrying particles to theelectrically-resistive switching layer in response to a stimulus,wherein the particle donor layer has an electrical resistivity of about0.5 milliohm (mohm)-centimeter (cm) or greater; and a top electrode,wherein: the top electrode, particle donor layer, electrically-resistiveswitching layer and bottom electrode are disposed electrically inserial.
 2. The non-volatile memory cell of claim 1, wherein thecurrent-carrying particles form a conductive filament through theelectrically-resistive switching layer in response to the stimulus,switching the non-volatile memory cell into a conductive state.
 3. Thenon-volatile memory cell of claim 2, wherein the non-volatile memorycell exhibits an inherent current limit in the conductive state.
 4. Thenon-volatile memory cell of claim 3, wherein the current limit is afunction of at least one of: a resistance of the particle donor layer;the electrical resistivity of the particle donor layer; or an effectivesurface area over which the conductive filament is in electrical contactwith the particle donor layer at a boundary of the particle donor layerand the electrically-resistive switching layer.
 5. The non-volatilememory cell of claim 3, wherein the inherent current limit prevents anincrease in current greater than about 0.1 milliamps through thenon-volatile memory cell in response to an input voltage meeting orexceeding a resistance voltage, wherein the resistance voltage is largerthan a program threshold voltage associated with the non-volatile memorycell transitioning from a resistive state to the conductive state. 6.The non-volatile memory cell of claim 3, wherein the inherent currentlimit prevents an increase in current greater than about 0.1 milliampsthrough the non-volatile memory cell following transition to theconductive state, for voltages at least as large as about 3 voltsapplied to the non-volatile memory cell.
 7. The non-volatile memory cellof claim 2, wherein the conductive filament becomes electricallynon-continuous between the top electrode and the bottom electrode inresponse to a second stimulus of opposite polarity as the stimulus. 8.The non-volatile memory cell of claim 2, wherein a width of theconductive filament within the electrically-resistive switching layer isindependent of a node size of the non-volatile memory cell.
 9. Thenon-volatile memory cell of claim 2, wherein a width of the conductivefilament within the electrically-resistive switching layer is less thanabout 10 nanometers.
 10. The non-volatile memory cell of claim 1,wherein the electrically-resistive switching layer comprises a materialhaving a resistivity of about 500 mohm-cm or greater.
 11. Thenon-volatile memory cell of claim 10, wherein the particle donor layeris comprised of a material selected from a group consisting of: TiN_(x),TaN_(x), AlN_(x), CuN_(x), AgN_(x), TiO_(x), TaO_(x), AlO_(x), CuO_(x),AgO_(x), TiO_(a)N_(b), AlO_(a)N_(b), CuO_(a)N_(b), WO_(a)N_(b) andAgO_(a)N_(b) where x, a, and b are suitable positive numbers.
 12. Thenon-volatile memory cell of claim 11, wherein the material of theelectrically-resistive switching layer includes a material selected froma second group consisting of: a silicon bearing material, a solidelectrolyte, SiO_(y), AlN_(y), TiO_(y), TaO_(y), AlO_(y), CuO_(y),TiN_(X), TiN_(y), TaN_(x), TaN_(y), SiO_(y), AlN_(x), CuN_(x), CuN_(y),AgN_(x), AgN_(y), TiO_(x), TaO_(x), AlO_(x), CuO_(x), AgO_(x), andAgO_(y), where y>x.
 13. The non-volatile memory cell of claim 1, whereinthe resistivity of the particle donor layer is within a range of about0.5 mohm-cm and about 100 mohm-cm.
 14. The non-volatile memory cell ofclaim 1, wherein the bottom electrode comprises a material selected fromthe group consisting of: TiN, TaN, W, TiW, WN and an alloy of theforegoing.
 15. A semiconductor device, comprising: a semiconductorsubstrate including a plurality of complementary metal oxidesemiconductor (CMOS) devices; and a resistive memory device disposedupon the semiconductor substrate and connected to a CMOS device of theplurality of CMOS devices, wherein the resistive memory devicecomprises: a bottom electrode; a resistive switching material layerdisposed upon the bottom electrode, wherein the resistive switchingmaterial layer comprises a plurality of defect locations, and wherein aresistivity for the resistive switching material layer is larger thanabout 0.5 ohm-cm; and a metal donor layer disposed upon the resistiveswitching material layer, wherein the metal donor layer comprises metalatoms and a metal compound, wherein a plurality of metal atoms from themetal donor layer diffuse to defect locations from the plurality ofdefect locations in the resistive switching material, and wherein themetal donor layer is characterized by a resistivity within a range ofabout 0.5 milliohm-cm to about 0.1 ohm-cm; and a top electrode disposedupon the metal donor layer.
 16. The semiconductor device of claim 15,wherein the metal atoms are selected from a group consisting of: Ti, Ta,Al, Cu and Ag.
 17. The semiconductor device of claim 16, wherein: themetal donor layer comprises a metal nitride: MN_(x); the resistiveswitching layer comprises a metal nitride: MN_(y); and y is larger thanx.
 18. The semiconductor device of claim 16, wherein: the metal donorlayer comprises a metal oxide: MO_(x); the resistive switching layercomprises a metal oxide: MO_(y); and y is larger than x.
 19. Thesemiconductor device of claim 16, wherein: the metal compound isselected from a group consisting of: MN_(x) and MO_(x); and theresistive switching material comprises SiO_(y), where y is anon-stoichiometric value.
 20. The semiconductor device of claim 15,wherein the bottom electrode comprises one or more materials selectedfrom a group consisting of: TiN, TaN, W, TiW, WN and an alloy of TiN,TaN, W, or TiW.